We have identified the forces that are necessary and sufficient to produce the keyhole shape of the Newt embryo neural plate from a hemispheric sheet of cells one cell thick. These forces are: 1) a regionally programmed shrinkage of the surface of the neural plate (accomplished by contraction of the apical surfaces of the neural plate cells and elongation of the cells perpendicular to the plate); 2) displacement of the whole sheet caused by elongation of the notochord of the overlying neural plate in the anterior-posterior direction. Since each cell in the neural plate contributes to the motion of the whole sheet, we used a computer simulation and mathematical analysis ('morphodynamics') to deduce the morphogenesis of the neural plate from the behavior of its component cells.